[DonRotolo]

Consumer Reports has a guideline on Repair or Replace when it comes to appliances, which kind of applies here.
I regret that I can only paraphrase it, since I don't subscribe any more.

Basically, you depreciate the item according to its lifetime. Let's say at your rate of usage the washer will last 20 years. 8/20 is 40% of its value is gone, so it is worth (.60 x $300) or $180.

You're going to spend $150 to repair a $180 item?

I have doubt the pump can be welded - it is likely an aluminum casting, and that's not a trivial weld to get right.

Can you sell the engine? If you can get $75 or $100 for it, does that change the equation?

Keep the old hose and wand as a spare - or use it and keep the brand new one as the spare.

Another game-changer: Can you find the pump cheaper somewhere? eBay and the interweb are miraculous, poke around a little and see what you get.

Last comment: try to figure out why it broke, so you can try to avoid it next time.